The Minister for Foreign Affairs, Dermot Ahern, has said he is seriously concerned about Iran's unilateral decision to resume nuclear research activities.
Mr Ahern said the move would jeopardise further talks between Iran and the international community to find an agreed solution consistent with safeguards set down by the United Nations nuclear watchdog.
The British Foreign Secretary, Jack Straw, said a meeting of foreign ministers from Britain, France and Germany to discuss the matter should take place on Thursday.
Mr Straw said he does not envisage the use of military action against Iran and told the House of Commons that such plans were not on the agenda.
Earlier, Iran defied warnings from the international community by removing United Nations seals from its nuclear plant in Natanz.
Officials from the UN nuclear agency, the International Atomic Energy Agency, were present as the seals were removed.
The White House has said if Iran continues with its nuclear work, the international community would have no choice but to refer Tehran to the UN Security Council for possible sanctions.
The move came even though the head of the IAEA, Mohammed ElBaradei, had called on Iran not to proceed with the work.
However, an official from Iran's own atomic energy body, Mohammad Saidi, denied any dispute with the IAEA chief.
The resumption ends a two-year suspension of research.
Western countries fear Iran's nuclear programme could be used to make atomic bombs, but Tehran denies this.
The European Union said Iran's actions violated an agreement with Europe not to undertake sensitive nuclear activities.
Both Russia and France have called on Tehran to keep its commitments on the nuclear issue.
The French President, Jacques Chirac, said Iran would be committing a serious error if it did not cooperate with the international community.
The US Ambassador to the IAEA, Gregory Schulte, said that Iran's move had shown disdain for international concern over the country's nuclear programme.
Russia has said dialogue was still the only way forward.
